It's easy to get wrapped up in the rating system. Seen a few creators (both here and in several discord servers) kinda fall into a rabbit hole trying to beat the system, believing this was how readers saw their work.
Fact of the matter -- the system is easily abused. Like easily and often.
During Webtoon contests of ANY kind, readers (and surprisingly some creators) are downvoting other comics to make sure their favorites gain more popularity. Even without contests, this still happens.
There's no rhyme or reason as to why someone will downvote you, and even if they had a reason, you're never gonna see it. The system doesn't allow people to leave written reviews to why they upvoted or downvoted something. So you can't even indicate what you need to improve on (if you even need to) unless people comment.
Additionally, its overall grading system has become real unhealthy. I was in a discord server with a creator who kept freaking out if they got anything less than a 9.5 rating. And for some readers, if you got a 7, they just assume your comic isn't worth its salt. It reminds me too much of school and how people kinda work themselves to the bone for grades.
All in all, it's not a good indicator of a comic's actual work. At least not on Webtoons.
If someone can't be bothered to comment on why they may or may not like your stuff and just leaves a rating, it doesn't really help you improve even if you wanted to. So I say don't even sweat it